I'm Stéphane, a senior product designer at Stack Exchange. This community went through the first phase of graduation back in Sep. 2015 and now we're ready to give you the second phase; a unique crafted site design and increase in the amount of reputation needed to access each privilege. I know this site already graduated, but I'll say it again...
We wanted to come up with a unique logo that could reflect any kind of signal processing topic (biological, chemical, electrical, mechanical...), so the icon had to be generic enough not to exclude some subjects, but the overall logo had to be unique.
To do so, we combined a wave sign with a specific typeface and added a gradient that convey the lifetime of a signal.
T-shirt and stickers
We believe the design and branding will work well for this community, that it's unique, and captures the correct mood. We’d love to hear your feedback, and if there are no major design changes, we’ll launch the new design and increase the site's required rep levels for privileges.
Thank you for for making this such a great community!
UPDATE: September 19, 2016
We posted a second option for the site's color palette, please vote for your favorite on that post!